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| Titel |
Using geophysics on a terminal moraine damming a glacial lake: the Flatbre debris flow case, Western Norway |
| VerfasserIn |
I. Lecomte, I. Thollet, H. Juliussen, S.-E. Hamran |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7340
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| Digitales Dokument |
URL |
| Erschienen |
In: 2nd EGU Alexander von Humboldt Conference "The role of Geophysics in Natural Disaster Prevention" ; Nr. 14 (2008-04-24), S.301-307 |
| Datensatznummer |
250012118
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| Publikation (Nr.) |
 copernicus.org/adgeo-14-301-2008.pdf |
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| Zusammenfassung |
| A debris flow occurred on 8 May 2004, in Fjǽrland, Western Norway, due
to a Glacial Lake Outburst Flood and a natural terminal moraine failure. The
site was investigated in 2004 and 2005, using pre- and post-flow aerial
photos, airborne laser scanning, and extensive field work investigations,
resulting in a good understanding of the mechanics of the debris flow, with
quantification of the entrainment and determination of the final volume
involved. However, though the moraine had a clear weak point, with lower
elevation and erosion due to overflowing in the melting season, the sudden
rupture of the moraine still needs to be explained. As moraines often
contain an ice core, a possible cause could be the melting of the ice,
inducing a progressive weakening of the structure. Geophysical
investigations were therefore carried out in September 2006, including
seismic refraction, GPR and resistivity. All methods worked well, but none
revealed the presence of ice, though the depth to bedrock was determined. On
the contrary, the moraine appeared to be highly saturated in water,
especially in one area, away from the actual breach and corresponding to
observed water seepage at the foot of the moraine. To estimate future
hazard, water circulation through the moraine should be monitored over time. |
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